Neurological outcome remains a major limiting factor in the quality of life following an ischemic insult to the brain; e.g., in stroke or after cardiac arrest and resuscitation. The differing susceptibility of various regions of the brain to ischemia is well known but the precise mechanisms are not clear. A critical factor leading to delayed irreversible neuronal death in selectively vulnerable regions of the brain is considered to be the prolonged inhibition of total protein synthesis. While the total protein synthesis is reduced, the expression of a family of heat shock proteins. (HSP) is actually enhanced in the postischemic brain during reperfusion. The mechanisms of these changes are not clear. Specifically, it is not understood whether there are regional differences in the expression of inducible heat shock proteins in the postischemic brain following reperfusion, and whether their induction helps to explain the resistance of certain neuronal populations to postischemic injury. The specific aims of this project are to characterize the time course of changes in mRNA expression of HSP-70 in comparison with that of alphatubulin, beta-actin, and poly A+ in various regions of differing susceptibility in the postischemic brain at various reperfusion periods. Ischemia will be produced in gerbils by bilateral common carotid artery occlusion for 10 min and will be followed by reperfusion for 0 min, 15 min, 1 h, 6 h, 1, 2, and 7 days. The expression of mRNA for HSP-70, alpha-tubulin, beta-actin, and Poly A+ will be localized & quantitated in specific cell types in hippocampus, cortex, caudate & thalamus of the brains of nonischemic controls and of postischemic gerbils with and without reperfusion, by in situ hybridization. Quantitation of the message will be performed by utilizing an image analyzer. The changes in mRNA will also be studied by Northern blot hybridization. Quantitative morphologic neuronal damage scores will also be obtained in selected regions of the brains and correlated with the changes in mRNA. Results obtained in the first 4 yrs of this study will provide a better understanding of the basic molecular changes in the neurons and will serve as a baseline for evaluating the efficacy of selected therapeutic agents in the 5th yr. Long term goal is to develop specific therapy for amelioration of ostischemic neurologic damage.